The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Most end users or institutional customers of cable high speed Internet (HSI) services use dynamically allocated Internet Protocol (IP) addresses for their customer premises equipment (CPE) devices, such as computers, gateway routers, etc. However, some cable HSI customers require static IP addressing. For example, if a customer is hosting a web server then the customer may prefer to have a static IP address assignment, or the customer may require a static IP in order to configure a secure VPN tunnel to remote locations.
The IP address ranges available for cable customers depend upon the IP subnets configured on the Cable Modem Termination System (CMTS) that services the CPE devices. IP subnets are assigned to logical interfaces, which are then referenced by the physical interfaces to which the cable modems are connected. Each CMTS is configured with its own set of IP subnets; consequently, if a cable modem is moved from one location to another that is serviced by a different CMTS than the first location, the cable modem's IP address must change. Moving a group of cable modems from one CMTS to another CMTS happens regularly due to increases in bandwidth requirements where additional CMTS devices are introduced in order to offload traffic.
The impact of such a move between CMTS devices is transparent to customers with dynamically allocated IP address assignments. In particular, when the CPE interface resets, the CPE will re-perform a Dynamic Host Configuration Protocol (DHCP) address leasing process and obtain a new IP address from the available subnets on the new CMTS. However, no such address assignment process is performed for devices with static IP assignments. The cable service provider must change the IP addresses of these devices, and then contact each of these customers with the changes. Further, customers may have to change configuration data on their equipment and/or notify certain entities of the change in addresses. This process is time-consuming, error-prone, and often requires manually-initiated communication steps, making it undesirable.
Request for Comments (RFC) 3344 of The Internet Society and developed by the Internet Engineering Task Force (IETF) defines IP mobility functionality, but implementation requires modification of both the CMTS as well as cable modems.